[autobuild] use autoreconf instead of calling tools manually; add generated files to .gitignore

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2914 152afb58-edef-0310-8abb-c4023f1b3aa9
add "packdist.sh" script to build (pre-) releases

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@2915 152afb58-edef-0310-8abb-c4023f1b3aa9